1. Field of Invention
This invention relates to piston rings for use in internal combustion engines. More particularly, it relates to piston rings for use in high speed, high power diesel engines having the bearing face plasma jet sprayed with a bond coat of nickle-chromium and aluminum powder and a scuff and wear resistant coating comprised of aluminum oxide, titanium dioxide and ferric oxide.
2. Description of the Prior Art
Piston rings, including compression rings and the like, are coated on their bearing faces to enhance their performance characteristics. As diesel engines having higher power and speeds are coming into service it is important that a coating be found which exhibits the desired characteristics of durability, wear and scuff resistance.
Chromium plated rings are known in the art and have been used successfully in diesel engines for many years. However, chromium plating is relatively expensive especially in relation to the scuff and wear resistance properties. Certain other art coatings have exhibited either good scuff or wear resistance but not both properties. U.S. Pat. No. 3,697,091 discloses a coating comprised essentially of a mixture of aluminum oxide and titanium dioxide in specified percentages by weight. Although the coating disclosed in U.S. Pat. No. 3,697,091 did exhibit a certain degree of good wear and scuff resistance in tests, it is believed that these compositions do not exhibit the superior qualities demonstrated by the compositions of the present application. Further, it does not appear that the compositions of U.S. Pat. No. 3,697,091 have found commercial acceptance.